Gin'iro Rakko no Namida is the first long story by Okano Kaoruko (1929 -). Together with Nagai Nagai Pengin no Hanashi [A Long Long Story of Penguin] (1957) by Inui Tomiko or Itazura Rakko no Rokko [A Mischievous Sea Otter Rokko] (1968) by Kanzawa Toshiko, this book established the animal fantasy genre of novel length. It also showed the foresight to pay attention to the problems as well as the merits of civilization and the importance of the conservation of wild life.
  The setting is in the nineteenth century in Alaska. The protagonist is an eight-year-old Eskimo boy named Pirala. He is given a harpoon as a birthday present. His father teaches him the rule to keep the animals from extinction as well as the way of hunting. At the same time, a pod of sea otters live near the shore reef on the south of the island. They survive the reckless hunting for their skin, and live there unobserved by human beings. In the pod, there is a very active and curious boy otter, named Gin'iro [Silver]. In early summer, Gin'iro comes near to the island where the Eskimos live, and meets Pirala. Pirala and his father follow Gin'iro who is hunted by his enemy, and find where Gin'iro and his pod live. Pirala's father tells him not to say a word about the place so that nobody will hunt them until the pod grows in number.
  Soon after that, Pirala's father leaves for trading. Pirala, who is bored when his father is absent, tells his friend Saneck about the sea otters. People in the village soon know about the pod. With guns received from trading, they go hunting to get the highly valued skin of otters, in spite of their old rule to shoot only male otters older than five years. Pirala bitterly regrets his thoughtless act, and tries to flee Gin'iro and his pod.
  Gin'iro Rakko no Namida is the first volume of novels for children published by Jitsugyô no Nihon Sha. Okano was a scriptwriter for science movies. She described the growth of Pirala and Gin'iro using the technique of flash back and plural viewpoints. In 1964, this book received the NHK Award for Children's Literature, the Sankei Award for Children's Books and Publications, and the Award of the Association for Protecting Animals. In 1984, a private edition with a few changes was published.